The invention relates to apparatus and methods for optical detection. More particularly, the invention relates to apparatus and methods for combining multiple modes and methods of optical detection, postprocessing, and/or feedback loops in bioanalytical measurements.
The number of bioanalytical measurements performed in life science research is increasing dramatically. This increase is driven in part by advances in genomics and combinatorial chemistry, which have increased both the number of biological targets and the number of compounds for screening them. This increase also is driven in part by advances in assay technologies, especially relating to DNA interactions, protein and peptide interactions, and cell-based assays, which have pushed the number of bioanalytical measurements from hundreds in standard 96-well microplates to millions in even higher-density microplates.
The cost of bioanalytical measurements is roughly proportional to the amount of regent consumed and to the time spent preparing the reagents, performing the measurements, and analyzing the data. To reduce cost in these measurements, researchers are adopting homogeneous assays and miniaturizing assay volumes. Homogeneous (i.e., xe2x80x9cmix and measurexe2x80x9d) assays generally do not involve filtration steps, which add to the complexity and cost of the measurements. Miniaturizing assay volumes (i.e., miniaturization) generally involves a decrease in assay volume (typically from about 100-200 xcexcL to about 1-10 xcexcL) and/or an increase in microplate well density (typically from 96-well formats to 384, 864, 1536, 3456, or denser formats).
Although miniaturization can be an effective cost reduction strategy, smaller sample sizes and larger numbers of measurements generally require larger numbers of secondary measurements to validate the results of the primary measurements. Ideally, the primary measurements should not require secondary analysis; however, false positives must be identified and eliminated. In addition, it is desirable to reduce the frequency of false negatives because these constitute lost information. For example, in the high-throughput screening typically carried out in drug discovery operations, false positives must be identified and eliminated in secondary operations because, by definition, they will not lead to a viable drug. Additionally, false negatives result in an inability to collect information from the affected library compounds.
The invention provides apparatus and methods for combining multiple modes and methods of optical detection, postprocessing, and/or feedback loops in bioanalytical measurements.